In the operation of some integrated circuits, it is necessary to provide a voltage level on the integrated circuit which is higher than the highest voltage level provided by the power supplied to the integrated circuit. This higher voltage is known as "boosted" or "booted" (as an abbreviation for boot-strapped). A particular instance where a boosted signal is required is in the output buffering of N-type MOS circuits. In these circuits, the pull-up transistor is an N channel transistor. To provide a high output signal meeting operating specifications, the full positive supply voltage (V.sub.dd) must be provided. However, with the source of an N-type field effect transistor and the gate of the field effect type transistor connected to V.sub.dd, the maximum output voltage available on the drain of the N-type field effect transistor is V.sub.dd less V.sub.th, where V.sub.th is the threshold voltage of the field effect transistor. One method of solving this problem is to boost the voltage applied to the gate of the field effect transistor.
In order to pull the output voltage up to a full V.sub.dd voltage level, a voltage level greater than V.sub.th above V.sub.dd must be applied to the gate of the pull-up transistor. This voltage is generated by boosting the voltage applied to the gate of the field effect transistor. A common technique for boosting the voltage is a circuit where a capacitor is charged by applying the reference voltage of the circuit, V.sub.ss, to one plate of the capacitor and V.sub.dd to the other plate of the capacitor. The plate of the capacitor connected to V.sub.dd is also connected to the gate of the pull-up transistor. At the appropriate time for boosting, the V.sub.dd source to the high voltage plate of the capacitor is removed and the high voltage plate of the capacitor and the gate of the pull-up transistor are isolated. The voltage applied to the low voltage plate of the capacitor is then raised to V.sub.dd. The charge stored on the capacitor is then distributed between the capacitor and the gate of the pull-up transistor. Thus the voltage on the gate of the pull-up transistor is raised to a level higher than V.sub.dd. In order to turn the pull-up transistor off, the high voltage charge now on the gate of the pull-up transistor must be removed. This is usually done by providing a transistor which provides a conductive path from the gate to V.sub.ss at the appropriate time. However, this type of arrangement dissipates the charge on the gate of the transistor through to ground thus wasting the power used to generate the boosting charge.